Ray Tracing

 I am doing lots of renders for my 3D adult game Jenna's Virtual Life. I always wondered how these are actually being done and why it takes so much time to render. I found a very nice explanation of the ray tracing process here: https://www.scratchapixel.com/lessons/3d-basic-rendering/introduction-to-ray-tracing/how-does-it-work

There is also a basic implementation of the algorithm. Seems like a fun thing to try at some point :)